Up here we have a very high degree of transponder use. The systems all correspond, so you can get from Massachusetts to DC without ever needing to physically pay a toll if you have a transponder issued by any of those states. People LIKE using the transponders. But the thing is, if you only drive on toll roads once or twice a year, then they're probably not worth the fuss; which is why you always need an alternate system. Most of our toll plazas now have only one or two manned gates. Going completely unmanned and saying "if you don't have a transponder we will bill your license plate address" isn't the greatest system in the world but it would certainly suffice. Just make sure to work it out with your friend in advance if you're driving his car .... It'll also be interesting to see how much more difficult this makes life for the car rental agencies if it catches on.

What I wish is that more places would install the high-speed transponder arches that you can drive under and have the charge register at full highway speeds, without having to slow down for the damned booths, re-merge afterward, etc.